In hybrid or electric vehicles, a secondary battery such as a nickel hydride battery or lithium-ion battery is mounted as a power supply. Electric power from a secondary battery is converted by an inverter circuit to electric power for driving before being supplied to a motor. A secondary battery may be charged by regenerated electric power.
The amount of electric power obtainable from a secondary battery is significantly lowered in a low temperature environment such as in winter compared to under a normal temperature. Therefore, it has been an important object to study on how to obtain electric power from a secondary battery as effectively as possible at a low temperature.
Patent Document 1 noted below discloses a temperature adjustment device for a power supply device which includes two or more power storage elements connected adjacent to each other in parallel. When a temperature of the power supply device sensed by a temperature sensor is so low that an internal resistance may increase as high as to cause degradation in a charge/discharge performance, a mounted controller controls such that the charge/discharge operation is performed intensively by at least one of the two or more power storage elements. The temperature of the entire secondary battery in the parallel system is quickly increased by rapidly raising the temperature of the power storage element controlled to perform the intensive charge/discharge operation at the same time as raising the temperature of the adjacently-provided other power storage elements by using the heat generated from the power storage element controlled to perform the intensive charge/discharge operation.